All runing rather well now.
Installed a genuine copy of XP Pro and activated it with MS.
Installed all the drivers for the mobo.
Connected the machine to the rest of the home network, installed the local printer (but couldn't find the network printer [yet}.
Ran Windows update a few times to get SP2 and a few new tweaks - wasn't offered SP3 for some reason.
Then I notice the configuration.
There are two identical optical drives in SATA 4 and SATA 5, and a brand new, therefore totally empty until this occurrence), 500Gb HDD as SATA 1.
Windows partitioned the drive, installed the OS - but called it "Drive I" (India) and classes Drive C as a "Removable disk - no media".
I'm sure that is going to cause tears in the (near) future.